I can fill normally but I cannot use the "outline", "replace", and other commands. It tells me "replace is not a valid state for [block]"
Is there something that has to be enabled on this world for those commands to be valid?
Here's my exact syntax:
/fill ~ ~ ~ ~10 ~10 ~10 water replace air
'replace' is not a state for block minecraft:water
Using version 1.12.2
Back in 2017 the command needed data values or states for the blocks.
I never really understood how to use them but
/fill ~ ~ ~ ~10 ~10 ~10 water 0 replace air 0
seems to work.
Here's the link to an appropriate version of the Wiki page for the /fill command.